X-Git-Url: http://git.rohieb.name/skm-ma-ws1314.git/blobdiff_plain/9c0186068ed8d750cbae9dae7740f312a7663fe8..0da2bf8734aa0dfb4639f1f2cc07cb31893dd2c5:/sec-dns-extensions.tex

diff --git a/sec-dns-extensions.tex b/sec-dns-extensions.tex
index dae9770..93921fd 100644
--- a/sec-dns-extensions.tex
+++ b/sec-dns-extensions.tex
@@ -15,23 +15,24 @@ group\footnote{\url{http://zeroconf.org}}.
 \term{Multicast DNS} (mDNS)~\cite{rfc6762} describes an extension to the Domain
 Name System that allows DNS resource records to be distributed on multiple hosts
 in a network, therefore avoiding central authorities and enabling every host to
-publish its own entries. For that purpose, a special domain, usually
-named \code{.local}, is used.
+publish its own entries. For that purpose, a special top-level domain, is used,
+usually named \code{.local}, which contains those entries.
 
 Software that supports mDNS listens on the reserved
 link-local multicast address \code{224.0.0.251} (for IPv4 queries) or
-\code{FF02::FB} (for IPv6 queries) on UDP port 5353 for incoming queries.
+\code{ff02::fb} (for IPv6 queries) on UDP port 5353 for incoming queries.
 Queries sent to those multicast address and port are standard DNS queries.
 If a host receives a query and knows about the queried resource, it responds to the
 querying host with a standard DNS response. The querying host can then simply
 finish and use the result, or wait until other hosts respond to its query. The
 latter is typically the case when a record can have multiple values, as it is
-the case with \code{SRV} and \code{PTR} records.
+the case with \code{SRV} and \code{PTR} records (which will be discussed in the
+next section).
 
 Another feature of Multicast DNS is the reduction of traffic through
 \term{Known-Answer Suppression}. It allows a querying host to specify already
 known resources in its query when querying resources that could exist on more
-than one host (e.~g., SRV records). The hosts matching those resources then do
+than one host (e.\,g., SRV records). The hosts matching those resources then do
 not generate a response, thus reducing the messages in the network and saving
 bandwidth, which is usually a scarce resource in wireless networks.
 
@@ -43,14 +44,12 @@ the network of new services available on a host.
 
 As another recent extension for the Domain Name System, \term{DNS-Based Service
 Discovery (DNS-SD)}~\cite{rfc6763} uses DNS records of types
-SRV~\cite{rfc2782} and PTR in a way that allows hosts to browse
-for services in a domain. This is a two-step process, consisting of
+SRV~\cite{rfc2782} and PTR~\cite{rfc1035} in a way that allows hosts to browse
+for services in a domain. While SRV records specify the location of services on
+a host, PTR records hold a reverse mapping from IP address to host name.
+DNS-SD now relies on a two-step process, consisting of
 \term{Service Instance Enumeration} and \term{Service Instance Resolution}.
 
-%\todo{XMPP is a probably not the best example here, use IPP instead}
-%\begin{subfigure} \end{subfigure} \begin{figure}[top] \centering
-%\includegraphics[width=0.9\textwidth]{fig-dnssd-mock.jpg} \caption{DNS-SD:
-%Service Instance Enumeration and Resolution} \label{fig:dnssd} \end{figure}
 \paragraph{1. Service Instance Enumeration} At first, to enumerate the available
 services in a domain for a given protocol, a DNS-SD-enabled client queries
 PTR resources of the form \code{\_service.\_proto.domain}. The result of