there is a problem is with the ipa-client 

https://fedorahosted.org/freeipa/ticket/1100

This fix is not included in RHEL 5.7 ipa-client, therefore it is not possible
to verify this bug.

Same result with RHEL 5 ipa-client scratch build:

ipa-client-install --domain=testrelm --realm=QWQW -p mysecret -w mysecret -U --server=ipaserver.testrelm
DNS domain 'qwqw' is not configured for automatic KDC address lookup.
KDC address will be set to fixed value.

Discovery was successful!
Realm: QWQW
DNS Domain: testrelm
IPA Server: ipaserver.testrelm
BaseDN: dc=qwqw



kinit(v5): Cannot contact any KDC for realm 'QWQW' while getting initial credentials

# rpm -q ipa-client
ipa-client-2.0-15.el5

ipa-server: RHEL 6.1  ipa-server-2.0.0-23.el6.x86_64
ipa-client: RHEL 5.7  sssd-1.5.1-36.el5 ipa-client-2.0-15.el5

# ipa-client-install --domain=testrelm --realm=QWQW -p admin -w mysecret -U --server=ipaserver.testrelm
DNS domain 'qwqw' is not configured for automatic KDC address lookup.
KDC address will be set to fixed value.

Discovery was successful!
Realm: QWQW
DNS Domain: testrelm
IPA Server: ipaserver.testrelm
BaseDN: dc=qwqw



Enrolled in IPA realm QWQW
Created /etc/ipa/default.conf
Configured /etc/sssd/sssd.conf
Configured /etc/krb5.conf for IPA realm QWQW
Warning: Hostname (client.testrelm) not found in DNS
Failed to update DNS A record. (Command '/usr/bin/nsupdate -g /etc/ipa/.dns_update.txt' returned non-zero exit status -6)
Failed to stop the NSCD daemon
SSSD enabled
Kerberos 5 enabled
NTP enabled
Client configuration complete.

# kinit jennyg
Password for jennyg@QWQW: 
Password expired.  You must change it now.
Enter new password: 
Enter it again: 

# cat /etc/ipa/default.conf 
#File modified by ipa-client-install

[global]
basedn = dc=qwqw
realm = QWQW
domain = testrelm
server = ipaserver.testrelm
xmlrpc_uri = https://ipaserver.testrelm/ipa/xml
enable_ra = True

# cat /etc/sssd/sssd.conf 
[sssd]
services = nss, pam
config_file_version = 2

domains = testrelm
[nss]

[pam]

[domain/testrelm]
cache_credentials = True
krb5_realm = QWQW
ipa_domain = testrelm
id_provider = ipa
auth_provider = ipa
access_provider = ipa
chpass_provider = ipa
ipa_server = _srv_, ipaserver.testrelm

# cat /etc/krb5.conf
#File modified by ipa-client-install

[libdefaults]
  default_realm = QWQW
  dns_lookup_realm = false
  dns_lookup_kdc = false
  rdns = false
  ticket_lifetime = 24h
  forwardable = yes

[realms]
  QWQW = {
    kdc = ipaserver.testrelm:88
    admin_server = ipaserver.testrelm:749
    default_domain = testrelm
    pkinit_anchors = FILE:/etc/ipa/ca.crt
  }

[domain_realm]
  .testrelm = QWQW
  testrelm = QWQW

[appdefaults]
  pam = {
    debug = false
    ticket_lifetime = 36000
    renew_lifetime = 36000
    forwardable = true
    krb4_convert = false
  }

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0975.html